In recent years, digital lines that can transmit/receive audio information and video information via a multichannel system such as the ISDN (integrated services digital network) have been in commercial use. In line with such a trend, the video telephone apparatus has come into widespread use. The video telephone apparatus is composed of at least transmitter means for transmitting images picket up via image pick-up means and associated voice data from the local party or user of the video telephone apparatus to the distant party, receiver means for receiving images and associated voice data from the distant party, and display means for displaying the images on a display and so on. While a liquid crystal panel is used as the display means based on the advantages of lightweight and low-profile design, the liquid crystal panel has a nature that it has a narrower angle of visibility than that of the CRT tube and that the angle of visibility differs between vertical direction and horizontal direction due to the properties of the liquid crystal material thus the angle on one side is further narrowed. As a result, there occurred such a problem as viewers in the center among a plurality of viewers could view a crisp image but the remaining viewers could not.
To solve such a problem, the Japanese Patent Laid-Open No. 56424/1993 disclosed video telephone apparatus comprising a selector circuit and a rotary plate. In this disclosure, the selector circuit was used to invert the inputs of picture signals to a horizontal side and a vertical side of the liquid crystal panel and the rotary plate was used to change the vertical-horizontal physical relationship of the liquid crystal display with the video telephone apparatus in order to conveniently view the images displayed on the crystal display panel formed in a rectangle whose vertical length differs from the horizontal length.
FIG. 9 shows the configuration of conventional video telephone apparatus. The conventional video telephone apparatus is composed of a crystal display panel 22 used as a monitor for displaying image information, a selector circuit 23 for switching between the horizontal direction and the vertical direction of an image displayed on the liquid crystal panel 22, and a rotary plate mounting the liquid crystal panel 22. The selector circuit 23 inverts the inputs of picture signals to a horizontal side and a vertical side of the liquid crystal panel 22 and switches between the horizontal direction and the vertical direction of an image displayed on the liquid crystal panel 22. The rotary plate 24 changes the vertical-horizontal physical relationship of the liquid crystal display 22 with the video telephone apparatus by rotating the liquid crystal panel mounted thereon.
Via such a configuration, it is possible for liquid crystal display such as a liquid crystal panel whose directivity of angle of visibility is inevitable to provide image display that efficiently uses the nature of the angle of visibility, by changing the vertical-horizontal relationship while properly maintaining the horizontal-vertical display relationship of an image.
When placing a call by using such video telephone apparatus, in particular a video telephone apparatus that can be transported, the user makes conversation with the receiver of the video telephone apparatus applied to his/her ear (hereinafter referred to as close-talking) or with the video telephone apparatus main unit placed on a desk, etc., without holding it in order to use the apparatus mainly as a video telephone set (hereinafter referred to as hands-free talking). The shape of portable video telephone apparatus is mostly a rod-like rectangular parallelepiped. In case the user makes conversation for example via hands-free talking, he/she often places video telephone apparatus in a fixed, stable state, that is, with the longitudinal direction of the enclosure placed horizontally or vertically with the mounting surface.
As mentioned earlier, the orientation of the video telephone apparatus main unit differs with the form of talking and the orientation of the image pick-up means and the display means provided on the video telephone apparatus main unit also differs accordingly. Thus, it is necessary to process and transmit an image picked up by image pick-up means so that the image may be in a normal orientation and the image may be displayed in a normal orientation on the display means.
However, via the aforementioned video telephone apparatus, it is impossible to change the orientation of an image picked up by image pick-up means (hereinafter simply referred to as a picked-up image) and change the orientation of an image received from the distant party (hereinafter referred to as a received image) on display means, according to the form of talking. Thus, problems arise that a picked-up image is transmitted to the distant party with the orientation of the image left unnatural and that the image is displayed in an unnatural orientation.
The invention solves the problems and aims at providing video telephone apparatus where the orientation of a picked-up image or a received image can be changed via the orientation of image pick-up means or display means so that a proper image can be always transmitted or displayed.
Another object of the invention is to provide video telephone apparatus that allows selection of proper receiver means and transmitter means appropriate according to the orientation of image pick-up means or display means, that is, selection between close-talking as a talking form where received voice data is regenerated by a receiver used in the close proximity of the user's ear and transmitted voice data is collected by a microphone used in the close proximity of the user's mouth, and hands-free talking where received voice data is regenerated by a received used away from the user's ears and transmitted voice data is collected by a microphone used away from the user's mouth.